std::ranges::views::join_with, std::ranges::join_with_view

 

C++

Compiler support

Freestanding and hosted

Language

Standard library

Standard library headers

Named requirements

Feature test macros (C++20)

Language support library

Concepts library (C++20)

Diagnostics library

Memory management library

Metaprogramming library (C++11)

General utilities library

Containers library

Iterators library

Ranges library (C++20)

Algorithms library

Strings library

Text processing library

Numerics library

Date and time library

Input/output library

Filesystem library (C++17)

Concurrency support library (C++11)

Execution control library (C++26)

Technical specifications

Symbols index

External libraries

 

Ranges library

Range access begin cbegin   end cend rbegin crbegin   rend crend size ssize   data cdata reserve_hint (C++26)   empty

Range conversions std::from_range_t std::from_range (C++23)(C++23)     to (C++23)

Dangling iterator handling dangling borrowed_iterator_t borrowed_subrange_t

Range primitives
range_size_trange_difference_trange_value_t elements_of (C++23)	iterator_tconst_iterator_tsentinel_tconst_sentinel_t (C++23)(C++23)	range_reference_trange_const_reference_trange_rvalue_reference_trange_common_reference_t (C++23)

Range concepts
range borrowed_range    common_range	sized_range viewable_range    view	input_range output_range forward_range	bidirectional_range    random_access_range contiguous_range	approximately_sized_range (C++26) constant_range (C++23)

Views
view_interface	subrange

Range factories
empty_viewviews::empty	single_viewviews::single	basic_istream_viewviews::istream	iota_viewviews::iota	repeat_viewviews::repeat (C++23)(C++23)

Range adaptors
views::all_tviews::all as_rvalue_viewviews::as_rvalue (C++23)(C++23)   filter_viewviews::filter transform_viewviews::transform take_viewviews::take take_while_viewviews::take_while common_viewviews::common views::counted as_input_viewviews::as_input (C++26)(C++26)	ref_view drop_viewviews::drop drop_while_viewviews::drop_while lazy_split_viewviews::lazy_split split_viewviews::split join_viewviews::join join_with_viewviews::join_with (C++23)(C++23)   concat_viewviews::concat (C++26)(C++26) cache_latest_viewviews::cache_latest (C++26)(C++26)	owning_view reverse_viewviews::reverse as_const_viewviews::as_const (C++23)(C++23) elements_viewviews::elements keys_viewviews::keys values_viewviews::values enumerate_viewviews::enumerate (C++23)(C++23) zip_viewviews::zip (C++23)(C++23) zip_transform_viewviews::zip_transform (C++23)(C++23)	adjacent_viewviews::adjacent (C++23)(C++23) views::pairwise (C++23) adjacent_transform_viewviews::adjacent_transform (C++23)(C++23) views::pairwise_transform (C++23) chunk_viewviews::chunk (C++23)(C++23) slide_viewviews::slide (C++23)(C++23) chunk_by_viewviews::chunk_by (C++23)(C++23) stride_viewviews::stride (C++23)(C++23) cartesian_product_viewviews::cartesian_product (C++23)(C++23)

Range generators std::generator (C++23)

Range adaptor closure objects range_adaptor_closure (C++23)

Range adaptor objects

Helper items
copyable-box movable-box (until C++23)  (C++23)	simple-view non-propagating-cache

 

std::ranges::join_with_view

Member functions

join_with_view::join_with_view

join_with_view::base

join_with_view::begin

join_with_view::end

Deduction guides

Iterator

Member functions

join_with_view::iterator::iterator

join_with_view::iterator::operator*

join_with_view::iterator::operator++ join_with_view::iterator::operator++(int) join_with_view::iterator::operator-- join_with_view::iterator::operator--(int)

Non-member functions

operator==(join_with_view::iterator) (C++23)

iter_move(join_with_view::iterator) (C++23)

iter_swap(join_with_view::iterator) (C++23)

Sentinel

join_with_view::sentinel::sentinel

operator==(join_with_view::sentinel) (C++23)

 

Defined in header <ranges>
template< ranges::input_range V, ranges::forward_range Pattern > requires ranges::view<V> && ranges::input_range<ranges::range_reference_t<V>> && ranges::view<Pattern> && /*concatable*/<ranges::range_reference_t<V>, Pattern> class join_with_view : ranges::view_interface<join_with_view<V, Pattern>>	(1)	(since C++23)
namespace views { inline constexpr /* unspecified */ join_with = /* unspecified */; }	(2)	(since C++23)
Call signature
template< ranges::viewable_range R, class Pattern > requires /* see below */ constexpr ranges::view auto join_with( R&& r, Pattern&& pattern );		(since C++23)
template< class Pattern > constexpr /* range adaptor closure */ join_with( Pattern&& pattern );		(since C++23)

1) A range adaptor that represents view consisting of the sequence obtained from flattening a view of ranges, with every element of the delimiter inserted in between elements of the view. The delimiter can be a single element or a view of elements.

For the definition of /*concatable*/, see std::ranges::concat_view.

2) RangeAdaptorObject. The expression views::join_with(e, f) is expression-equivalent to join_with_view(e, f) for any suitable subexpressions e and f.

See More

join_with_view models input_range.

join_with_view models forward_range when:

• ranges::range_reference_t<V> is a reference, and
• V and ranges::range_reference_t<V> each model forward_range.

join_with_view models bidirectional_range when:

• ranges::range_reference_t<V> is a reference,
• V, ranges::range_reference_t<V>, and Pattern each models bidirectional_range, and
• ranges::range_reference_t<V> and Pattern each model common_range.

join_with_view models common_range when:

• ranges::range_reference_t<V> is a reference, and
• V and ranges::range_reference_t<V> each model forward_range and common_range.

Nested types

Type	Definition
InnerRng	ranges::range_reference_t<V> (exposition-only member type*)

Data members

Member	Definition
V base_	the underlying (adapted) view (exposition-only member object*)
Pattern pattern_	the pattern object (exposition-only member object*)
non-propagating-cache <ranges::iterator_t<V>> outer_it_ (present only if V does not model forward_range)	the cache of the outer iterator (exposition-only member object*)
non-propagating-cache <std::remove_cv_t<InnerRng >> inner_ (present only if std::is_reference_v<InnerRng > is false)	the cache of the inner range (exposition-only member object*)

Member functions

(constructor)	constructs a join_with_view (public member function)
base	returns a copy of the underlying (adapted) view (public member function)
begin	returns an iterator to the beginning (public member function)
end	returns an iterator or a sentinel to the end (public member function)
Inherited from ranges::view_interface
empty	returns whether the derived view is empty, provided only if it satisfies sized_range or forward_range (public member function of std::ranges::view_interface<D>)
cbegin (C++23)	returns a constant iterator to the beginning of the range (public member function of std::ranges::view_interface<D>)
cend (C++23)	returns a sentinel for the constant iterator of the range (public member function of std::ranges::view_interface<D>)
operator bool	returns whether the derived view is not empty, provided only if ranges::empty is applicable to it (public member function of std::ranges::view_interface<D>)
front	returns the first element in the derived view, provided if it satisfies forward_range (public member function of std::ranges::view_interface<D>)
back	returns the last element in the derived view, provided only if it satisfies bidirectional_range and common_range (public member function of std::ranges::view_interface<D>)

Deduction guides

Nested classes

iterator	the iterator type (exposition-only member class template*)
sentinel	the sentinel type (exposition-only member class template*)

Notes

Feature-test macro	Value	Std	Feature
__cpp_lib_ranges_join_with	202202L	(C++23)	std::ranges::join_with_view

Example

Run this code

#include <iostream>
#include <ranges>
#include <string_view>
#include <vector>

int main()
{
    using namespace std::literals;
    
    std::vector v{"This"sv, "is"sv, "a"sv, "test."sv};
    auto joined = v | std::views::join_with(' ');
    
    for (auto c : joined)
        std::cout << c;
    std::cout << '\n';
}

Output:

This is a test.

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR	Applied to	Behavior as published	Correct behavior
LWG 4074	C++23	join_with_view was underconstrained	updated the constraints

See also

ranges::join_viewviews::join (C++20)	a view consisting of the sequence obtained from flattening a view of ranges (class template) (range adaptor object)
ranges::concat_viewviews::concat (C++26)	a view consisting of concatenation of the adapted views (class template) (customization point object)